Incidence of and risk factors for surgical site infection after colorectal surgery: A multiple-center prospective study of 3,663 consecutive patients in China.

BACKGROUND: Surgical site infection (SSI) after colorectal surgery (CRS) remains a significant problem for its negative clinical outcomes. However, it is poorly understood in China. This study aims to investigate the incidence, risk factors and microbiology of SSI after CRS. METHODS: A nationwide prospective multicenter design was applied. Patients in 19 Chinese hospitals from 2015 to 2018 were prospectively monitored for SSI after CRS. Demographic data, hospital characteristics, and potential perioperative risk factors were collected and analyzed, using univariate and multivariate logistic regression models. RESULTS: Among 3,663 study participants, 134(3.66%) episodes of SSI were identified. The incidence rate of SSI decreased from 5.9 infections per 100 procedures in 2015 to 3.1 infections per 100 procedures in 2018 (incidence rate ratio, 0.52; 95% CI, 0.28-0.94). The SSI rates were 1.88, 4.15, 6.27 and 11.58 per 100 operations for the National Nosocomial Infections Surveillance system (NNIS) risk index categories of 0, 1, and 2 or 3, respectively. Escherichia coli (54/134, 40.3%) and Klebsiella pneumoniae (10/134, 7.5%) were the most frequently isolated microorganisms. A high prevalence of antibiotic resistance were observed in our study, with rates of extended spectrum beta-lactamase-producing or carbapenem-resistant Escherichia coli and Klebsiella pneumonia of 50.0%(27/54) and 30.0%(3/10) respectively. Preoperative hospital stay ≥ 48h (OR=2.28, 95% CI: 1.03-5.02, P=0.042) and contaminated or dirty wound (OR=3.38, 95% CI: 1.88-6.06, P=4.50×10-5) were significantly associated with increasing risk of SSI after CRS. CONCLUSION: A statistically significant but modest decrease in the incidence rate of CRS SSI over the 4-year study period was observed in this study. Noticeably, the relatively high rates of multidrug-resistant pathogens causing SSI after CRS should be alert, while more studies with large population are needed due to the small number of isolates identified in our survey.

[MicroRNA-3963 Promotes Adipogenic Differentiation of Mouse-Derived Mesenchymal Stem Cells].

OBJECTIVE: To investigate the effect of MicroRNA-3963(miR-3963) on the adipogenic differentiation of mouse bone-derived mesenchymal stem cells(MSC). METHODS: MSCs were isolated from C57BL/6 mice bone fragment and transfected with miR-3963 mimic, miR-3963 inhibitor and negative control. The expression of miR-3963 and transfection efficiency were detected by q-PCR. These transfected cells were induced to adipocytes and stained with oil red O after 14 days culture. q-PCR and Western blot were used to detect the expression of adipogenic differentiation marker genes C/EBPα and PPARγ at transcriptional level and protein level. RESULTS: The results of q-PCR revealed that miR-3963 expression level was up-regulated after transfection with miR-3963 mimic (P<0.0001), and down-regulated after transfection with miR-3963 inhibitor (P<0.0001). After oil red staining, overexpression of miR-3963 in MSCs could promote the formation of lipid droplet. The q-PCR and Western blot analyses showed the significant increase of expression of adipogenic marker genes C/EBPα and PPARγ in MSC transfected with miR-3963 mimic. Additionally, compared with the control group, miR-3963 inhibitor could decrease adipogenic differentiation of MSC. CONCLUSION: miR-3963 can regulate and promote adipogenic differentiation of mouse bone-derived MSC.

[Effect of MicroRNA-146b-5p on Adipogenesis of Mouse Bone Essence Derived Mesenchymal Stem Cells].

OBJECTIVE: To explore the effect of MicroRNA-146b-5p (miR-146b-5p) on the mouse bone essence derived MSC adipogenic differentiation. METHODS: MSC were isolated from bone essence of C57BL/6 mice. The expression level of miR-146b-5p in the process of adipogenic differentiation of MSC was detected by q-PCR; the role of miR-146b-5p mimics or inhibitors in the process of mouse bone essence derived MSC adipogenic differentiation was analyzed through oil red staining the expression of C/EBPα and PPARγ after cultured for 14 days was detected by q-PCR; the protein level of PPARγ after miR-146b-5p transfection was detected by Western blot. RESULTS: The MSC were successfully isolated from bone essence of mice, the q-PCR results showed an increasing expression level of miR-146-5p in the process of MSC adipogenic differentiation. Compared with the control group, MSC transfected with miR-146b-5p mimic could up-regulate the expression of miR-146b-5p (P<0.001), while miR-146b-5p inhibitor transfection could down-regulate the endogenous miR-146b-5p expression (P<0.01). After culture for 14 d, the result of Oil red staining showed that the miR-146b-5p inhibitor could inhibit adipogenic differentiation, while the miR-146b-5p mimic could promote the adipogenic differentiation of MSC. After induction for 14 d, compared with control, the PPARγ and C/EBPα in mimic group were higher expressed PPARγ and C/EBPα (P<0.01). Compared with induced group, the PPAPγ and C/EBPα were lower expressed in inhibitor group (P<0.05). The results of Western blot showed that the expression level of PPARγ was high in minic group, and it was low in inhibitor group. CONCLUSION: miR-146b-5p is up-regulated in the process of MSC adipogenic differentiation, and it promotes the adipogenesis of MSC originated from mouse bone essence.